Diffractive display

ABSTRACT

The present invention is directed to an improvement in a diffractive display suitable for presenting graphic and the like displays. Broadly, a novel embodiment is realized from a holographic diffraction pattern carried by a magnet or element and an electrically energizable coil magnetically coupled with said magnet that is energizable for movement of the magnet. Rotation of the holographic diffraction pattern generates a display using the diffracted light from the holographic diffraction grating. Another novel embodiment is realized from a faceted rotatable element (FRE) having an array of facets each bearing a diffraction grating and a source energizable for rotation of the FRE from a resting station to a viewing station. Rotation of the FRE generates a display using the diffracted light from the diffraction gratings.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is cross-referenced to commonly-assignedapplication Ser. No. ______, filed on even date herewith (AttorneyDocket No. LUC 2-026), the disclosure of which is herein incorporated byreference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to an improvement to a diffractivedisplay (reflective or transmissive) wherein each pixel exhibits a fullrange of diffracted wavelengths (e.g., full range of colors) by a noveldiffractive technique.

[0003] The art is replete in proposing graphics displays which utilize,for example, bimorph elements or, simply, bimorphs, or equivalents. Abimorph is a device manufactured with two strips of piezoelectric filmwhich are fastened together and which have electrodes allowingelectrical fields of the proper polarity to be applied to the film tocause an electrostrictive effect to occur. Such electrostrictive effectcan be an in-plane elongation or contraction, or an out-of-planedeflection of one end of the film when the opposite end is secured.

[0004] U.S. Pat No. 4,331,972 proposes a light valve comprising a pairof elements of transparent material, each comprising a diffractiongrating of light periodicity facing each other with parallel gratinglines. Such light valve is termed a bigrate in this patent. Thetransmission of light through the bigrate will depend on the relativeposition of the pair of gratings in the direction perpendicular to thegrating lines. One of the gratings may be embossed on a bimorph film ofpolyvinylidene fluoride and moved by the application of a voltagethereto. One strip, then, may be moved relative to the other in responseto an electrical signal to control the zero diffraction or the lighttransmission from no transmission to full transmission, or any desiredintermediate transmission. Three different superimposed bigrated lightvalves are used for achieving the three different colors required for acolor display, viz., cyan, magenta, and yellow.

[0005] U.S. Pat. No. 5,067,829 proposes to steer light beams by passingthe light beams through optically transparent elastic material which arebent under the application of a voltage which bending or deformationcauses the change in the angle at which the light beam intercepts thesurfaces of the optically transparent layers.

[0006] U.S. Pat No. 5,052,777 utilizes a bimorph as a shutter to pass orblock light coupling therethrough. Such bimorph shutters permit light,such as transmitted through optical fibers, to be coupled through thebimorph light valves to an observer for generating graphic displays.

[0007] U.S. Pat No. 4,274,101 discloses a laser recorder that utilizes apiezoelectric bimorph focal length vibrator.

[0008] U.S. Pat. No. 5,126,836 proposes a television display wherein awhite light source emits a beam onto a plurality of dichroic mirrorswhich split the beam into three beams of primary colors, then reflectsthe primary beams onto three deformable reflective surfaces which may bepiezoelectric crystals, which again reflect the beams through slits in anon-reflective surface, thereby modulating the intensity of the beams.U.S. Pat No. 4,415,228 also proposes a bimorph light valve, as does U.S.Pat. No. 4,234,245.

[0009] Additional proposals include Stein, et al, “A Display Based onSwitchable Zero Order Diffraction Grating Light Valves”, Advances inDisplay Technology V, SPI vol. 526, 105-112 (1985), which propose a flatpanel display which utilizes a matrix of line addressable light valvesback-lighted with a partially collimated source. The basic pixel elementof the display is an optical switch based on the zero order ofdiffraction by two aligned transmission phase gratings. The transmissionof light is modulated by mechanically displacing one grating withrespect to the other by one-half of the grating. A bimorph is used forthis purpose.

[0010] Finally, another proposal is by Gale, et al., “DiffractiveDiffusers for Display Application”, Current Developments in OpticalEngineering and Diffraction Phenomena, SPIE vol. 679, 165-168 (1986),which propose diffractive optical diffusers for display applicationswherein the diffusers can be fabricated by laser beam writingtechniques.

[0011] The foregoing techniques function to some degree to providegraphic displays; however, a much improved technique for creating suchdisplays is disclosed in U.S. Pat. No. 5,613,022, by Odhner, et al.,entitled “Diffractive Display and Method Utilizing Reflective orTransmissive Light Yielding Single Pixel Full Color Capability,” issuedMar. 18, 1997. Through movement of a diffraction grating, this techniquecan be used to create graphic displays, each pixel of the display beingcapable of full color. A diffuser panel or image surface can beilluminated by the pixel for enhancing viewing of the display by anobserver.

[0012] While this diffractive technique represents an advancement in thefield of graphics displays, there still exists a real need in the artfor additional ways to implement this approach in order to make suchdiffractive displays economical and practical, especially when producedin large volume.

[0013] Broad Statement of the Invention

[0014] The present invention is directed to an improvement in adiffractive display suitable for presenting graphic and the likedisplays. Broadly, a novel embodiment is realized from a holographicdiffraction pattern carried by a magnet or element and an electricallyenergizable coil magnetically coupled with said magnet, which isenergizable for movement of the magnet. Rotation of the holographicdiffraction pattern generates a display using the diffracted light fromthe holographic diffraction grating.

[0015] Another novel embodiment is realized from a faceted rotatableelement (FRE) having an array of facets each bearing a diffractiongrating and a source energizable for rotation of the FRE from a restingstation to a viewing station. Rotation of the FRE generates a displayusing the diffracted light from the diffraction gratings.

[0016] One configuration for the FRE is a substantially flat, circularplate having a plurality of posts about its periphery each of whichbears a diffraction grating. Alternately and preferably, however, anyarray of diffraction gratings each having a different spacing,preferably in the form of holographic diffraction gratings, may bedisposed along the surface of the plate. Other configurations may beutilized which, because of their reduced mass, increase rotation speedand decrease acceleration and deceleration periods to enable each pixelto alternate between or among colors rapidly. Rotation of the FRE may berealized through the use of, for example, a stepper motor or linearactuator.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] For a fuller understanding of the precepts and advantages of thepresent invention, reference is made to the description that followstaken in conjunction with the accompanying drawings in which:

[0018]FIG. 1 is a top view of a pixel utilizing the improved rotatingmagnet and fixed, energizable coil embodiment;

[0019] FIGS. 2A-2C illustrate the rotation of a magnet from an initialposition to two different positions;

[0020]FIG. 3 is a side view of the pixel of FIG. 1 which shows theconnection of a magnet and coil to a printed circuit board;

[0021] FIGS. 4A-4E show a number of methods for attaching a magnet anddiffractive grating;

[0022]FIG. 5 illustrates a partial view of light being diffracted from asource to an eye station by a faceted rotating element (FRE);

[0023] FIGS. 6A-6E shows a number of FRE configurations each composed ofa support portion and a faceted surface portion;

[0024]FIG. 7 is a perspective view of an FRE in combination with severalconventional display elements;

[0025]FIG. 8A is a perspective view of an FRE connected to a steppermotor;

[0026]FIGS. 8B and 8C are perspective views of an FRE connected to alinear actuator;

[0027]FIG. 9A is a perspective view of an FRE having a singlediffraction grating;

[0028]FIG. 9B is a perspective view of the FRE of FIG. 9A being rotatedfrom an initial position to a second position; and

[0029]FIG. 9C is a perspective view of the FRE of FIG. 9A being rotatedfrom an initial position to a third position.

[0030] The drawings will be described in detail below.

DETAILED DESCRIPTION OF THE INVENTION

[0031] A unique method for creating graphics displays is disclosed inU.S. Pat. No. 5,613,022, by Odhner, et al., entitled “DiffractiveDisplay and Method Utilizing Reflective or Transmissive Light YieldingSingle Pixel Full Color Capability,” issued Mar. 18, 1997 (hereinafterreferred to as “the '022 patent”). Using this technique, a diffractiongrating, carried by an electroactive or magnetoactive film, is connectedto an energy source that is energizable for movement of the film. Thediffraction grating will diffract a particular color when illuminated bya broad band source at a particular angle. Movement of the film carryingthe diffraction pattern will change the angle of incident light to thediffraction grating. This will cause the beam diffracted at a givenangle to change its wavelength. For a broad band visible light source(although the present invention is equally applicable to ultraviolet (orUV) and infrared wavelengths of energy), it is possible to cause a pixelto reflect the colors, inter alia, red, green, and blue, as a functionof the rotation of the diffraction grating.

[0032] In order to achieve color uniformity and a wide field of view,this grating should be a hologram of, e.g., ground glass, photographicfilm, or the like. The diffracted color is determined by the gratingequation:

λ=d(sin τ+sin δ)

[0033] where,

[0034] λ=wavelength of diffracted light (microns)

[0035] d=grating spacing of one cycle (microns)

[0036] τ=angle of incidence from plate normal (degrees)

[0037] δ=angle of diffraction from plate normal (degrees)

[0038] For a fixed δ and a fixed d, the wavelength will vary withchanges in τ.

[0039] A number of implementations to effect movement of the diffractiongrating are disclosed in the '022 patent. One embodiment involves theapplication of a voltage to a piezoelectric material to which adiffraction grating is attached causing the material to bend varying theeffective spacing of the diffraction grating. The deflection of the filmbeing proportional to the voltage applied. Other embodiments employmagnets and energizable coils to provide deflection of a diffractiongrating according to the principles of electromagnetics. Each of thespecifically described variations of the magnetic approach in the '022patent includes fixed permanent magnets and a rotatable coil to which adiffraction grating is affixed. Interaction of the permanent magnets'fields and the magnetic field generated by the coil provide the forcethat causes the coil, and thus the diffraction grating, to rotate.

[0040] While the embodiments disclosed in the '022 patent may beproduced satisfactorily for most commercial purposes, the art alwaysstrives to develop improvements which are more practical and efficient.In testing an embodiment using a fixed coil and a moving magneticcomponent to which a diffraction grating is attached, unexpected resultswere achieved. It is expected that providing a fixed coil and movingmagnet, instead of a fixed magnet and moving coil, would result inequivalent performance. However, using the moving magnet approachunexpected and beneficial results were realized including smaller massrelative to torque produced and less power dissipation, less hingematerial variance in spring constant and conductivity, fewer productionquality control issues, and lower production process costs.

[0041] Looking now to FIG. 1, a top view of a pixel, shown generally at90, is revealed to include the improved moving magnet embodiment. Adiffraction grating is provided at 100. This diffraction grating may bea holographic film. Diffractive grating 100 is attached to a magneticcomponent that is a permanent magnet (shown at 120 in FIGS. 2 and 3).Diffractive grating 100 may be physically attached to magnet 120 or,alternatively, diffractive grating 100 and magnet 120 each may beaffixed to an additional element to form the attachment. Magnet 120rests upon pivot 140 which is made of ferromagnetic material and,therefore, attracts magnet 120 and holds it in place while stillallowing the tilting motion to take place about pivot 140. Connectingto, part of, or adjacent to, pivot 140 is current carrying conductor 160that is connected to FET (field effect transistor) 170. As such, magnet120 and coil 160 are magnetically coupled.

[0042] With current flowing through wire 160, a magnetic field iscreated which exerts a force on magnet 120. Because magnet 120 is not ina permanently fixed position, the force created by the current in wire160 will cause magnet 120, and associated diffractive grating 100, torotate about pivot 140. The direction of rotation of magnet 120, andassociated diffractive grating, about pivot 140 depends on the directionof the magnetic field associated with magnet 120 and the direction ofcurrent flowing through wire 160. Reversing the polarity of the currentin wire 160 changes the direction of the force created, causing themagnet to rotate in the opposite direction. Wire 160 may consist ofmultiple turns, however, for efficiency purposes, the coil preferablyconsists of a single turn. Electromagnetic shielding 260 is providedaround each pixel to prevent the interaction of fields generated byneighboring pixels or external sources (so-called “cross-talk”). Thisshielding may be composed, for example, of SAE 1010 steel. As will beobvious to one skilled in the art, alternative configurations can beenvisioned to electromagnetically couple magnet 120 and coil 160 formovement of the magnet. Several illustrative configurations aredescribed in greater detail later.

[0043] Turning briefly to FIGS. 2A-2C, magnet 120 is shown rotated totwo different positions. Numeration contained in FIG. 1 is retained. InFIG. 2A, magnet 120 is in an initial position normal to pivot 140, asindicated by the dashed line 180. When current flows through wire 160 inthe direction indicated in FIG. 1, magnet 120 will be rotated from itsinitial position through an angle, θ₁, to the position shown in FIG. 2B.By reversing the polarity of the current flowing through wire 160,magnet 120 will be rotated through an angle, θ₂, in the oppositedirection as shown in FIG. 2C. Generally, the magnet will need to rotateonly about 8 degrees in either direction to achieve a full color pixel.

[0044] Returning to FIG. 1, stops 200 and 210 prevent the rotation ofmagnet 120 beyond desired bounds. A portion of magnet 120 has been cutaway to reveal the presence of stop 210. Stop 210 may include acapacitance probe or sensor which senses the presence of a capacitor(not shown), for example, composed of aluminized Mylar®, which islocated below magnet 120 and indicates the position of magnet 120. Oncethe magnet has been driven to a desired position, it is held in place bythe magnetic fields surrounding ferromagnetic pins 220 and 240. Becauseof the presence of these pins, magnet 120 may be held in position withlittle or no current flowing in wire 160.

[0045] Turning now to FIG. 3, a side view of the pixel of FIG. 1 isshown revealing the connection of the above-described elements to aprinted circuit board. Numeration from FIG. 1 is retained. Printedcircuit board (PCB) 280 is seen to have ground plane 300 and +voltagebus 320. FET 170 is connected in series with conductor 160, groundconnector 360 and +voltage connector 340 (FIG. 1) being connected toground plane 300 and +voltage bus, respectively. Similarly, thecapacitance sensor located on stop 210 is connected to ground plane 300at 400 and +voltage bus 320 at 380. The connection of elements to PCB280 is intended to be illustrative and not limiting of the presentinvention, as it will be obvious to those skilled in the art that otherarrangements may be provided.

[0046] Turning to FIGS. 4A-4F, alternate configurations of the magneticcomponent are revealed. FIG. 4A shows the configuration utilized in FIG.1 wherein diffraction grating 500 is affixed directly to permanentmagnet 502. For fabrication purposes, carrier 504 may be interposedbetween magnet 502 and diffraction grating 500 as shown in FIG. 4B.

[0047] For the two previous magnet configurations, a single magnet isprovided whose dimensions extend co-extensively with those of thesupported diffraction grating and carrier, if a carrier is included. Amagnet having lesser dimensions also may be used. In addition, wheremultiple coils are provided, other configurations are possible usingmultiple permanent magnets located in various positions relative to thediffraction grating. The magnetic component also could be provided inthe form of discrete magnetic particles dispersed or embedded in anydesired concentration throughout the carrier. For illustrative purposes,several possible magnet configurations are shown in FIGS. 4C-4E. In eachof these figures, the reference number 506 indicates a permanent magnet,while reference numerals 508 and 510, respectively, indicate thepresence of a diffraction grating and a carrier. Carrier 510 is shown inthese figures as having a rectangular shape with upper surface 520,lower surface 522, front edge 524, and rear edge 526. The description ofcarrier 510 as being rectangular, however, is intended in anillustrative and not a limiting sense as the geometry of carrier 510 maybe varied. With multiple magnets and multiple coils, the interaction ofthe resulting magnetic fields may be different from that described withrespect to FIG. 1; therefore, some modification of the system may berequired. However, with the appropriate modification, uniqueconfigurations may be designed by one skilled in the art which, whilemimicking the electromagnetic technique shown in FIG. 1, take advantageof extra driving forces to achieve special effects.

[0048] In the course of developing the moving magnet embodiment based onthe electromagnetic concepts disclosed in the '022 patent, it wasdiscovered that the unique use of diffraction gratings to create graphicdisplays could be implemented in a slightly different fashion. Whilethis implementation is an approximation of the '022 approach,significant structural advantages may be realized. These advantages maybe actualized through the utilization of a faceted rotatable element(FRE) designed to diffract one of a select number of colors to anobserver when illuminated by a broad band source at a particular angle.A facet, provided on a rotatable base or element, is a region or areahaving a diffraction grating with a particular grating spacing which,when illuminated by a broadband light source, diffracts a particularcolor to an observer. An array of facets may be achieved on the FRE byproviding an array of diffraction gratings each of which may have adifferent spacing wherein each diffraction grating element of the arraymay be disposed in juxtaposition or may be spaced apart, or by using aholographic diffraction grating array wherein the array of facets aresuperimposed. In its simplest embodiment, however, the FRE may have asingle diffraction grating disposed upon its surface, each change inposition of the FRE representing a facet. Those skilled in the art willappreciate that there is any number of practical methods forimplementing the FRE approach. The rotating element may be, for example,a plate having a surface and a periphery, which is connected to anenergy source such as a linear actuator or stepper motor, which effectsrotation of the plate. A single diffraction grating or an array ofdiffraction gratings, each element of such array having a differentgrating spacing or a superimposed array of holographic diffractiongratings, may be disposed along the surface of the plate; oralternatively, posts, each of which supports a diffraction grating, maybe located about the periphery of the plate. A select number of theconceivable FRE configurations are described in greater detail in thefollowing figures. These too are intended as illustrative and notlimiting of the present invention.

[0049] While the facets may be randomly placed along or across the FRE,the location of each facet within the array is known. For example, eachlocation can be stored in the memory of a microprocessor. With thelocation of each facet in the array known, the FRE may be rotated suchthat the light source illuminates a select-facet to diffract aparticular color of interest.

[0050] Turning to FIG. 5, an FRE having an array of facets in the formof posts extending around its periphery, is shown illuminated by a broadband source. The FRE, shown generally at numeral 600, is seen to havesurface portion 602 and support portion 604. Surface portion 602 iscomposed of an array of facets 606 a-606 f, each of which bears adiffraction grating. These gratings diffract light from broad bandsource 622. The lengthwise extent of each facet extends greater thanthat of the supported diffraction grating, such that an amount of spaceor a rest station, such as that shown generally at 621, is createdbetween adjacent diffraction gratings. Each rest station may represent anull position or may be used to provide a background color when an imageis not being displayed. Each of diffraction gratings 608, 610, 612, 614,616, and 618 has a unique grating spacing to diffract a particular coloras seen by the viewer at eye station 620. FRE 600 is rotatable about anaxis normal to the surface of support portion 604 which may be at itscenter of gravity, at an edge, at its center, or in any other desiredposition. The location of the axis of rotation, such as that shown at624, will in part depend on the geometry and construction of supportportion 604. Rotation of FRE 600 may be in either a clockwise orcounterclockwise direction; however, rotation in either direction aboutan origin provides the greatest efficiency.

[0051] FRE 600 initially is positioned at a rest station. From thisinitial rest station position, FRE 600 is rotated to a viewing stationwherein a diffraction grating is located at origin 626. In FIG. 5,diffraction grating 614 is located at origin 626 so that diffractedlight of a particular color will be seen at eye station 620. This light,for example, may be blue. To diffract a different color to eye station620, FRE 600 is rotated from one viewing station past a resting stationto another viewing station. Because each diffraction grating has aunique grating spacing, incident light from source 622 will bediffracted at a different angle associated with a particular color.Light diffracted from grating 616 carried by facet 606 e may be green,while the light diffracted by grating 618 carried by facet 606 f may bered. The relative positioning of the facets with respect to origin 626determines the angle of rotation associated with each. To view greenlight at eye station 620, FRE 600 is rotated as indicated by angle θ₁.To view red light at eye station 620, FRE is rotated as indicated byangle θ₂, and so on. The number of discrete colors available to generatea graphics display is determined by the number of facets and associateddiffraction gratings provided along the surface portion of the FRE.

[0052] As illustrated in FIGS. 6A-6E, variations of the support portionand faceted surface portion may be utilized to create an FRE suited toany particular display application. In FIGS. 6A-6E, a support portionand surface portion are shown generally at numerals 700 and 702,respectively. FIG. 6A depicts substantially flat, circular plate 704having facets in the form of posts 706 a-706 d, which extend from itsouter periphery. A diffraction grating, for example formed from aphotoresist (holographic diffraction grating), is carried on the outerend of each post 706 a-706 d. Using a circular plate such as that atnumeral 704, the axis of rotation is most practically located throughthe plate's center identified by numeral 708. Alternately, only a partof the circle may be provided as the support portion, as shown in FIG.6B, with a faceted surface portion extending around its outer periphery.With this less massive configuration, the FRE may be rotated morequickly with less power required to commence and terminate rotation fromone diffraction grating to another. For this configuration, the centerof gravity is likely the most efficient location for the axis ofrotation. Given the more rapid rotation to a desired viewing station andmore efficient performance which may be obtained by reducing the mass ofthe FRE, it will be obvious to one skilled in the art that any number ofconfigurations may be provided for this purpose. Similarly, the numberof posts, or the number of diffraction gratings located on each post,may vary in accordance with the display purpose.

[0053] As another alternate, the FRE could have a lattice or gridlikemesh support portion as shown at numeral 710 in FIG. 6C. The supportportion also may have an open center as at 712, the surface portionbeing supported at its ends by support rods as at numerals 714 and 716.While the support portion of the FRE has been described as beingcircular or a section of a circle, FIG. 6E reveals a support potionhaving an angular geometry. The support portion may be designed in anyconfiguration that may be rotated about an axis and that is capable ofsupporting a faceted surface portion. The support portion, showngenerally at numeral 700 in FIGS. 6B-6E, may support a faceted surfaceportion such as that shown in FIG. 5 or may have facets comprising postsas in FIG. 6A.

[0054] Turning now to FIG. 7, an FRE is revealed in combination withseveral conventional display elements. The FRE, represented generally atnumeral 720 is composed of generally circular plate 722 with periphery724 and surface 726. While the FRE shown is shown and described ashaving a generally circular shape, other shapes may be proposed to suitdiffering display designs. The shape of the rotating element also may bechosen to maximize pixel density. A continuous diffraction grating isdisposed along surface 726. Diffraction grating 728 has three facets730, 732 and 734 each of which is associated with a particular color asseen by an observer. By rotating one of the facets to a viewing station,in similar fashion as that described above in connection with FIG. 5,light from a broad band source will be diffracted to an eye stationwhere a viewer will see the selected color. It is readily apparent thatmultiple facets disposed along the plate surface also may be provided bya plurality of diffraction gratings. In addition, for efficiencypurposes, a particular color may be repeated by placing more than onediffraction grating with associated grating along the plate surface.Multiple areas of a single color may minimize the response time requiredto rotate the plate to a viewing station where the desired color isdisplayed.

[0055] While the array of facets may be provided as a plurality of postsalong the periphery of the plate or as an array of diffraction gratingseach element of the array having a different grating spacing, anotherapproach is to superimpose the facets holographically. The array offacets is superimposed on a single photographic film, each facet beingangularly oriented or offset with respect to each other. Thus, theholographic film is developed such that at a given position of FRE 720with respect to the light source, a particular color is transmitted tothe observer or to a detector. For example, the colors red, blue, andgreen may be reconstructed by a single holographic element or pixel. Ifplate 722 is rotated, for example, 2° from an initial position of 0°,incident light is diffracted and the color blue will be seen transmittedto the observer. By rotating plate 722 to another position, for example,9° from its initial position, the observer will see the color green.Then, if the plate is rotated, for example, 17° from the initialposition, the color red will be transmitted to the observer. Additionalcolors (wavelengths of energy, both visible, IR and UV) may be generatedby holographically superimposing a greater number of facets of differentselect diffraction grating spacing on the surface of the plate.Similarly, additional colors (wavelengths of energy) may be achieved byoscillating plate 722 between two diffraction gratings, or colors, at agiven frequency such that observer perceives a third color.

[0056] As described in connection with FIGS. 5 and 6, the array offacets supported by an FRE is provided by a plurality of diffractiongratings. In its simplest form, however, an FRE with its array of facetsmay be a single diffraction grating. In FIGS. 9A-C, such an FRE isillustrated. Looking first to FIG. 9A, an FRE having the above-describedconfiguration is shown generally at 910 in combination with a broad bandlight source, 912. FRE 910 is fixed relative to light source 912 asshown in FIGS. 9A-9C. At a fixed location relative to FRE 910 is an eyestation, 914. When a select facet of FRE 910 is at a viewing station, aselect color generated by FRE 910 is seen by an observer at eye station914. By rotating the facets between a resting station and a viewingstation, i.e. by rotating FRE 910, individual colors are selectivelydisplayed at eye station 914.

[0057] To generate these different select colors or energies, FRE 910 iscomposed of a plate or disk, 913, and a single holographic diffractiongrating, 916, which has a constant grating spacing, 918. Diffractiongrating 916 is seen to be disposed across the surface of disk 913.Preferably, diffraction grating 916 is a holographic diffractiongrating. White light, as shown at 920, is generated by source 912 and,when incident on the surface of FRE 910, a spectrum or plurality ofcolors is generated by grating 916, as shown generally at 922. Forillustrative purposes, spectrum 922 is seen to include three colors,924, 926, and 928. In fact, spectrum 922 will include a multitude ofcolors. What range of the spectrum will be diffracted and the width ofeach color band will be determined by grating spacing 918.

[0058] While a plurality of colors are generated by grating 916 inconventional fashion, an observer at eye station 914 sees only one colorat a time. For example, in FIG. 9A, FRE 910 is revealed in an initialposition as indicated by line 920. At this initial position, the colorseen by observer 914 will, for example, be green. By rotating FRE fromits initial position to a second position, as shown in FIG. 9B, a secondcolor will be seen at eye station 914. If FRE 910 is rotated 7° from itsinitial position, for example, as indicated by arrow 932 extendingbetween lines 930 and 934, spectrum 922 shifts such that color 928 isseen at 914. This color, for example, may be red. As illustrated in FIG.9C, FRE 910 may be rotated to display a third color, for example beingrotated 8° in the opposite direction, as indicated by arrow 936extending between initial position 930 and third position 938. Thisthird color, for example, may be blue.

[0059] Each rotational position of FRE 910 represents a facet, a selectcolor being diffracted to an observer at eye station 914 for eachposition. As with the previous embodiments, when a facet is in aposition to display color to the observer, that facet is at a viewingstation. When a facet is not in a position to display color to theobserver, then that facet is at a resting station. Thus, in FIG. 9A thefacet associated with the color green is at a viewing station. The othertwo facets of FRE 910, i.e. those associated with the colors red andblue, each being at a resting station. In FIG. 9B, the facet associatedwith the color red is at a viewing station, while in FIG. 9C, the facetat the viewing station is the one associated with the color blue.

[0060] If the observer is properly positioned, as at 914 in FIGS. 9A-C,all of the colors that the FRE is capable of generating may beselectively displayed. That physical location, at which all of thecolors are separately viewable, will vary in size depending on the widthof each color band. As mentioned previously, the grating spacing of thediffraction grating will determine the range of the spectrum diffractedand the width of each color band. The greater the number of colorsgenerated, and thus the narrower the band of each color, the smaller thephysical area where the observer can be positioned to view all of thecolors. For example, if an FRE such as that shown and described inconnection with FIGS. 9A-C, is rotated too far from its initial positionin either direction, no color will be seen by observer 914.

[0061] Looking briefly at FIGS. 8A-8C, several mechanisms suitable torotate the FRE are shown. FIG. 8A reveals an FRE, such as that describedin connection with FIG. 6A, connected to a stepper motor. The steppermotor, shown generally at numeral 800, has spindle 802 that is connectedto center of circular plate 804. Microprocessor driven controller 806effectuates rotation of spindle 802 and associated plate 804 inpredetermined steps in a clockwise and/or counterclockwise direction.With each step, the plate may be rotated from a resting station to aviewing station or from one viewing station to another with the platepassing through a resting station. The resolution of the stepper motormust be at least equal to the number of diffraction gratings supportedby the faceted surface portion. Using an FRE with a stepper motoreliminates the need for position sensors, such as those used with themoving magnet embodiment. The microprocessor can store information aboutthe FRE's position by tracking the number of steps rotated in eachdirection. In addition to a stepper motor, any motive source capable oftranslating linear motion to rotational motion also may be used.

[0062] In FIG. 8B, plate 808 is shown connected to linear actuator 810.Like the stepper motor, linear actuator 810 is controlled bymicroprocessor 816. Linear motion of rod 818 is converted to rotationalmotion in conventional fashion, for example, by pulley 812 connectedbetween axle 813, about which the plate is rotated, and nut 814. Anotherconventional method for translating linear motion to rotary motion,illustrated in FIG. 8C, is achieved by connecting linear actuator 820 toplate 822 having arc accommodation. To effect rotational movement, rod824 of linear actuator 820 is connected to plate 822 by pin 826 withinslot 828. Pivoting the linear actuator about point 830 while moving pin826 within slot 828, the plate will rotate as shown by directional arrow832. If the slot is of sufficient dimensions, the linear actuator may befixed at point 830. Other methods for effecting rotational movement ofthe FRE, either of circular or of other shape, will be obvious to thoseskilled in the art.

[0063] Returning to FIG. 7, once an image has been generated asdescribed above, conventional elements may be utilized to create graphicdisplays and the like. With the FRE formed of transparent material, alight source may be positioned behind the FRE, as shown generally at336, to create a transmissive display. Alternatively, if FRE 720 is madeof reflective material, a light source may be positioned as showngenerally at 338 to create a reflective display. Creating bothtransmissive and reflective displays is discussed in greater detail inthe '022 patent. For either type of display, the image generated usingFRE 720 may be focused directly onto a diffusing element, such as shownat 340, by a lens assembly (not shown). Relatively little space isrequired between these elements allowing the construction of thindisplays. To produce a larger image, a greater amount of space betweenthese elements allows projection equipment, such as that shown at 342,to be interposed. Such projection equipment is well known in the art andeasily incorporated into a display utilizing the unique image generationtechniques.

[0064] The disclosure herein is illustrative of the present inventionthat should be understood to include various variations, modifications,and equivalents to those disclosed herein as those skilled in the artwill appreciate. In this application, all references are incorporatedherein by reference.

We claim:
 1. In a display comprising an element that carries aholographic pattern of a diffraction grating which element is associatedwith a source energizable for movement of said element, wherein saidholographic pattern is moved by movement of said element and whereinmovement of said holographic pattern diffracts energy incident on saidholographic pattern to generate different select diffracted energiesfrom said holographic pattern, the improvement which comprises: saidelement includes a magnetic component and said holographic pattern andhas a pivot point; and said source is fixed relative to said element andcomprises one or more electrically energizable coils magneticallycoupled with said magnetic component, said source being energizable tocause said element carrying said holographic pattern to rotate aboutsaid pivot point.
 2. The display of claim 1, wherein said selectdiffracted energies are projected by a projection system.
 3. The displayof claim 1, wherein the center of gravity of said element is thelocation of said pivot point.
 4. The display of claim 1, wherein saidpivot point is spaced-apart from the center of gravity of said element.5. The display of claim 1, wherein said one or more electricallyenergizable coils each consist of multiple turns.
 6. The display ofclaim 1, wherein said one or more electrically energizable coils eachconsist of a single turn.
 7. The display of claim 1, wherein saidmagnetic component comprises a permanent magnet having principaldimensions commensurate with said diffraction grating and saiddiffraction grating is affixed to said magnet.
 8. The display of claim1, wherein said magnetic component and said diffraction grating areaffixed to a carrier having a first surface, a second surface, a firstedge, and a second edge.
 9. The display of claim 8, wherein saiddiffraction grating is disposed along said first surface and saidmagnetic component is a permanent magnet disposed along said secondsurface.
 10. The display of claim 8, wherein: said magnetic componentincludes a first permanent magnet disposed along said first surfaceadjacent said first edge and a second permanent magnet disposed alongsaid first surface adjacent said second edge; and said energizable coilincludes a first coil magnetically coupled with said first magnet and asecond coil magnetically coupled with said second magnet.
 11. Thedisplay of claim 8, wherein: said magnetic component includes a firstpermanent magnet disposed along said first surface adjacent said firstedge and a second permanent magnet disposed along said second surfaceadjacent said second surface; and said energizable coil includes a firstcoil magnetically coupled with said first magnet and a second coilmagnetically coupled with said second magnet.
 12. The display of claim1, wherein said magnetic component comprises a carrier having pluralityof discrete permanent magnetic particles embedded within said carrier.13. In an apparatus comprising an element which carries diffractiongrating(s) which element is associated with a source energizable formovement of said element, wherein said diffraction grating(s) are movedby movement of said element and wherein movement of said diffractiongrating(s) diffract energy incident on said diffraction grating(s) togenerate different select diffracted energies from said diffractiongrating(s), the improvement which comprises: said element being afaceted rotatable element (FRE) having an array of facets each facet ofsaid array bearing a diffraction grating, and said FRE having a pivotpoint; said source being fixed relative to said FRE and energizable tocause a select facet of said array to be rotated, by rotation of saidFRE about said pivot point, from a facet resting station to a facetviewing station, whereat a select diffracted energy(s) is generated anddisplayed to an observer.
 14. The apparatus of claim 13, wherein saidsource is a stepper motor.
 15. The apparatus of claim 13, wherein saidsource is a linear actuator.
 16. The apparatus of claim 13, wherein saidFRE is a plate having a periphery bearing an array of facets, each ofsaid facets comprising a post carrying diffraction grating(s).
 17. Theapparatus of claim 13, wherein said FRE includes an arcuate portionbearing said array of facets and a support to which said arcuate portionis connected.
 18. The apparatus of claim 13, wherein the diffractiongrating(s) are holographic diffraction grating(s).
 19. The apparatus ofclaim 13, wherein said FRE is a plate having a surface and a periphery,said surface bearing said array of facets which are superimposedholographic diffraction grating(s), each facet being angularly offsetwith respect to each other.
 20. The apparatus of claim 13, wherein saidselect diffracted energies are projected by a projection system.
 21. Theapparatus of claim 13, wherein said FRE is rotated about its center. 22.The apparatus of claim 13, wherein said FRE is rotated about its centerof gravity.
 23. The apparatus of claim 13, further including an imagesurface spaced apart from said FRE upon which said select diffractedenergy(s) is focused to create a display.
 24. In a method for generatingdifferent select diffracted energies from an element which carries aholographic pattern of a diffraction grating which element is associatedwith a source energizable for movement of said element, wherein saidholographic pattern is moved by movement of said element and whereinmovement of said holographic pattern diffracts energy incident on saidholographic pattern to generate different select diffracted energiesfrom said holographic pattern, the improvement which comprises the stepsof: (a) providing said element to contain a magnetic component alongwith said holographic pattern, said element having a pivot point; (b)fixing said source relative to said element; (c) providing said sourceas one or more electrically energizable coils; (d) magnetically couplingsaid electrically energizable coil with said magnetic component; and (e)energizing said electrically energizable coils to cause said elementcarrying said holographic pattern to rotate about said pivot point andto generate said different select diffracted energies.
 25. The method ofclaim 24, which includes the step of projecting with a projection systemsaid generated different select diffracted energies onto a surface. 26.The method of claim 24, which further comprises the step of providingsaid one or more electrically energizable coils as multiple turn coils.27. The method of claim 24, which further comprises the step ofproviding said one or more electrically energizable coils as single turncoils.
 28. The method of claim 24, which further comprises the steps of:(f) providing said magnetic component as a permanent magnet havingprincipal dimensions commensurate with said diffraction grating; and (g)affixing said diffraction grating to said permanent magnet.
 29. Themethod of claim 24, which further comprises the steps of: (h) providinga carrier having a first surface, a second surface, a first edge, and asecond edge; and (i) affixing said magnetic component and saiddiffraction grating to said carrier.
 30. The method of claim 29, whichfurther comprises the steps of: (j) disposing said diffraction gratingalong said first surface of said carrier; (k) providing said magneticcomponent as a permanent magnet; and (l) disposing said permanent magnetalong said second surface.
 31. The method of claim 29, which furthercomprises the steps of: (m) providing said magnetic component as a firstpermanent magnet and a second permanent magnet; (n) disposing said firstpermanent magnet along said first surface adjacent said first edge; (o)disposing said second permanent magnet along said first surface adjacentsaid second edge; and (p) providing said energizable coil as a firstcoil magnetically coupled with said first magnet and a second coilmagnetically coupled with said second magnet.
 32. The method of claim29, which further comprises the steps of: (q) providing said magneticcomponent as a first permanent magnet and a second permanent magnet; (r)disposing said first permanent magnet along said first surface adjacentsaid first edge; (s) disposing said second permanent magnet along saidsecond surface adjacent said second edge; and (t) providing saidenergizable coil as a first coil magnetically coupled with said firstmagnet and a second coil magnetically coupled with said second magnet.33. The method of claim 24, which further comprises the step ofproviding said magnetic component as a having plurality of discretepermanent magnetic particles embedded within a carrier.
 34. In a methodfor generating different select diffracted energies from an elementwhich carries diffraction grating(s) which element is associated with asource energizable for movement of said element, wherein saiddiffraction grating(s) are moved by movement of said element and whereinmovement of said diffraction grating(s) diffracts energy incident onsaid diffraction grating(s) to generate different select diffractedenergies from said diffraction grating(s), the improvement whichcomprises the steps of: (a) providing said element as a facetedrotatable element (FRE) having an array of facets each bearing adiffraction grating, and said FRE having a pivot point; (b) fixing saidsource relative to said FRE; and (c) energizing said source to cause aselect facet of said array to rotate, by rotation of said FRE about saidpivot point, from a facet resting station to a facet viewing station,whereat a select diffracted energy(s) is generated for displaying to anobserver.
 35. The method of claim 34, which further comprises the stepof providing said source as a stepper motor.
 36. The method of claim 34,which further comprises the step of providing said source as a linearactuator.
 37. The method of claim 34, which further comprises the stepof providing said FRE as a plate having a periphery bearing an array offacets, each of said facets comprising a post carrying a diffractiongrating(s).
 38. The method of claim 34, which further comprises the stepof providing said FRE having an arcuate portion bearing said array offacets and a support to which said arcuate portion is connected.
 39. Themethod of claim 34, which further comprises the step of providing saiddiffraction grating(s) as holographic diffraction grating(s).
 40. Themethod of claim 34, which further comprises the step of providing saidFRE as a plate having a surface and a periphery, said surface bearingsaid array of facets which are superimposed as a holographic diffractiongrating(s), each facet being angularly offset with respect to eachother.
 41. The method of claim 34, which further comprises the step ofprojecting with a projection system said generated different selectdiffracted energies onto a surface.
 42. The method of claim 34, whichfurther comprises the steps: (d) providing an image surface spaced apartfrom said FRE; and (e) focusing said generated select diffractedenergy(s) onto said image surface to create a display.
 43. The apparatusof claim 13, wherein said FRE is a plate having a surface which bears aholographic diffraction grating of constant spacing and said platehaving an axis, said FRE being rotatable about said axis to a pluralityof facet viewing stations to create said array of facets, such that ateach facet viewing station a select diffracted energy(s) is generatedand displayed to said observer.
 44. The method of claim 34, whichfurther comprises the steps of: providing said FRE as a plate having asurface which bears a holographic diffraction grating of constantspacing and said plate having an axis, said FRE being rotatable aboutsaid axis to a plurality of facet viewing stations to create said arrayof facets, such that at each facet viewing station a select diffractedenergy(s) is generated and displayed to said observer.